Device for evaluating vehicle, driving and operating parameters

ABSTRACT

A device for evaluating vehicle, driving and operating parameters of a vehicle, in order to adjust the gear ratio of a transmission according to predetermined algorithms, parameters, or characteristic diagrams, selects anew the gear to be adjusted and adjusts the same by way of an evaluation in dependence upon criteria that are specific to the transmission.

The invention concerns a device for evaluating vehicle, driving andoperating parameters of a kind defined in a more detailed manner in thepreamble of claim 1.

The desire for a greater economy with a very good drivability requires abetter adaptation of the vehicle operating conditions in motor vehiclesto the most advantageous operating ranges of a driving engine. This isachieved by means of multi-speed or continuously variable transmissionshaving a great transmission range. In order to exploit the advantages,the speeds of the transmission should be optimally changed or shifted,which places high demands on the driver. If the continuously variabletransmission is treated as a transmission with infinite speeds, theconsiderations that are valid for continuously variable transmissionscan be transferred similarly, as a rule, also to multi-speedtransmissions. For purposes of simplicity, reference will be made in thefollowing embodiments especially to a multi-speed transmission and theterminology compatible therewith.

In order to relieve the driver and increase riding comfort, more andmore vehicles are being offered with a fully automated transmissionconsisting of an engine, a starter element, for example a clutch and/ora converter, a transmission with different gear ratios and a drive axlewith wheels. Part of the automation consists in selecting anadvantageous gear ratio for the respective operating condition of thevehicle and determining the correct shifting point. Economy and ridingcomfort should be taken into consideration at the same time.

Known automatically shifting step-by-step variable gears for motorvehicles are shifted automatically within the range of available speedsprimarily depending upon speeds that are proportional to the drivingspeed and upon load conditions, for example, the position of anaccelerator pedal or throttle pedal during idle, partial load, full loador kickdown. In order to reduce the number of shifting operations, thedriver can exclude speeds in the upper or lower range from the shiftingsequence via a selector switch, for example, while ascending a mountainor during winter operation.

Also known are systems in which the microprocessor electronics determinethe speed to be shifted in accordance with a predetermined computerprogram. If a high shifting characteristic or kickdown is reached in theshifting characteristic field, the electronics trigger a correspondingshifting operation. The torque of the engine is reduced during theshifting operation in order to burden the friction elements less andimprove shifting comfort. Several programs having different shiftingdiagrams are provided for different driving situations. The shifting canoccur automatically between the individual shifting diagrams. It is alsopossible to adapt the shifting characteristics in dependence uponoperating parameters.

Multi-speed transmissions, which are shifted with an interruption of thetractive force, are frequently used for utility vehicles. A controldevice for automatically shifting multi-speed, step-by-step variablegears is known, for example, from EP 0 255 519 B1, in which the shiftingpoints are fixed in dependence upon the vehicle speed, the torquerequirement (throttle lever position) and the acceleration determinedfrom the speeds of the gearbox output shaft.

The throttle pedal position is further divided into three regions,namely, into an idle region, a central region and a full load region. Toeach region of the throttle pedal position is allocated an accelerationregion so that under these prerequisites eighteen shifting pointsresult. The shifting conditions for the shifting points are retained intables wherein the values are determined empirically or by calculation.Several tables may be needed, depending on the number of runningprograms that are utilized.

From DE 197 03 561 A1, a device for evaluating vehicle, driving andoperating parameters is known, which makes a selection of gear ratiosavailable and can be utilized as a standard for different automaticallyshifting transmissions and requires a low synchronization effort. Thisdevice serves for evaluating the vehicle, driving and operatingparameters of a vehicle, in order to select and adjust a gear ratio of atransmission by means of a microprocessor in accordance with specificalgorithms, parameters or characteristic diagrams, wherein anacceleration of the vehicle is determined by calculation from the changeof the driving speed corresponding to the speed of a power train with anengine and a transmission.

The devices for evaluating vehicle, driving and operating parameters ofa vehicle that are known from the state of the art, which select andadjust a gear ratio of a transmission by means of a microprocessor inaccordance with predetermined algorithms, parameters, or characteristicdiagrams, have a disadvantage that they do not take into considerationamong the influence parameters any of the changes subjected todurability or service life. Gear selection thus occurs based onevaluation criteria that refer to the new condition, and not the changesin the transmission and on the vehicle caused by the operation.

It is the object of the present invention to outline a device forevaluating vehicle, driving and operating parameters of a vehicle, whichevaluates a gear ratio of a transmission according to predeterminedalgorithms, parameters, or characteristic diagrams, while taking intoconsideration specific transmission criteria and parameters; selects andadjusts the same by means of a microprocessor. The gear selectionoccurs, in particular, based on the evaluation criteria, which take intoconsideration the changes in the transmission and on the vehicle causedby the operation.

The object of the invention is attained by means of a device of thiskind for evaluating vehicle, driving and operating parameters, whichalso has the characteristic features of the main claim.

The gear selected and adjusted by the microprocessor based on thevehicle, driving and operating parameters is evaluated, selected andadjusted in dependence upon specific operating criteria. The evaluationcriteria are adapted especially to the properties of the transmission.The evaluation criteria can be, among other things, the service life orthe durability based on the different loads of different transmissioncomponents. Consequently, the actuation frequency of an actuator or asynchronization or also the service life design of a gear can be, forexample, a criterion for the selection of the next gear to be engaged inview of a load collective. Further criteria can be, among other things:noises, shifting times, the driving portions within the different gearratios, i.e., the length of time during which a specific drive positionis engaged; also the relationship to the lengths of time during whichother drive positions are engaged, the distribution of the temperaturesexisting in the transmission and the aging of the transmission oil,wherein the oil temperature, the drive-through capacity of thetransmission, the drive power that has passed through the transmissionand the driving portions within the different gear ratios are taken intoconsideration.

The invention is suitable for all vehicles having a fully automatic orpartially automatic drive train consisting of an engine with or withoutstarter element, e.g., a clutch and/or a converter, a transmission withdifferent gear ratios and a drive axle with wheels. The transmission canbe a continuously variable transmission, as well as a multi-speedtransmission, which is shifted with an interruption of the tractiveforce or under load.

The invention will be described in more detail in the following in viewof the exemplary embodiment depicted in the FIGURE.

The single FIGURE shows a drive train 1 and an engine 2, a starterelement, for example, a clutch or a converter 3, and a transmission 4.The transmission 4 can be a multi-speed or a continuously variabletransmission, which is shifted with an interruption of the tractiveforce and/or under load. A microprocessor 8 controls the drive units 2,3, and 4 of the drive train 1 in dependence upon operating parameters 5,drive parameters 6 and vehicle and transmission parameters 7, andgenerates output signals for an actuating element 9 of the engine 2, anactuating element 10 of the clutch 3, and an actuating element 11 of thetransmission 4 according to predetermined algorithms, parameters, orcharacteristic diagrams. To the operating parameters 5 belong, forexample, the position of an accelerator pedal, as a rule a throttle,their change over a period of time, as well as the acceleration of theaccelerator actuation, and braking and steering signals. To the drivingparameters 6 belong, for example, the flow rate of a fuel measuring unitor a load signal, an engine speed, an ignition angle adjustment, atemperature, for example, the coolant temperature, an aggregatetemperature, etc. To the vehicle and transmission parameters 7 belong aposition of the gear selector lever or a gear shifting or changingdevice of the transmission 4, a driving speed or a speed in the drivetrain associated therewith, longitudinal acceleration and transverseacceleration, load conditions, tractive resistances, and temperatures.Because of the vehicle and transmission parameters 7, a gear evaluation12 takes place, which selects the gear to be newly adjusted and adjuststhe same with the aid of the actuating element 11 of the transmission 4.

REFERENCE NUMERALS

1 drive train

2 engine

3 clutch/converter

4 transmission

5 operating parameters

6 driving parameters

7 vehicle and transmission parameters

8 microprocessor

9 actuating element for the engine

10 actuating element for the clutch

11 actuating element for the transmission

12 gear evaluation

1. (canceled)
 2. A device for evaluating vehicle, driving and operatingparameters of a vehicle, in order to select and adjust a gear ratio of atransmission by means of a microprocessor in accordance with one ofpredetermined algorithms, parameters, and characteristic diagrams, agear selected and adjusted by the microprocessor is evaluated, selectedand adjusted in dependence upon an actuation frequency of one of anactuator or service life design of the gear.